US3392451A

US3392451A - Dynamic railway track inspecting apparatus

Info

Publication number: US3392451A
Application number: US561163A
Authority: US
Inventors: Leo R Lombardo
Original assignee: Cleveland Technical Center Inc
Current assignee: Cleveland Technical Center Inc
Priority date: 1966-06-28
Filing date: 1966-06-28
Publication date: 1968-07-16
Anticipated expiration: 1985-07-16
Also published as: GB1136462A

Description

July 16, 1968 L. R. LOMBARDO 3,392,451

DYNAMIC RAILWAY TRACK INSPECTING APPARATUS Filed June 28, 1966 2 Sheets-Sheet l INVENTOR. 50 A. 04/5/4200 w aaotd M XW July 16, 1968 L. R. LOMBAIIRDO 3,392,451

DYNAMIC RAILWAY TRACK INSPECTING APPARATUS Filed June 28, 1966 2 Sheets-Sheet z Imp/Made r Pu/Je 70 Amp. flezecfor 5' 7 70 Amp- .DeZec for 56 INVENTOR. .450 P. ZOMBA F00 M MW;

United States Patent 1 3,392,451 DYNAMIC RAILWAY TRACK INSPECTING APPARATUS Leo R. Lombardo, Mayfield Heights, Ohio, assignor to Cleveland Technical Center, Inc., Cleveland, Ohio, a

corporation of Delaware FiledJune 28, 1966, Se'r. No. 561,163 13 Claims. (Cl. 33-145) ABSTRACT OF THE DISCLDSURE rejected.

This invention relates to measuring irregularities in the rails of railway track and more'particularly to a dynamic railway track inspecting apparatus employing electronic systems.

It is known in the art to employ railway track inspecting apparatus for sensing the vertical movements of a vehicle wheel on one track relative to a vehicle Wheel on the other track. Apparatus of this type is disclosed in such US. patents as Sperry Patent 1,837,633, Breznai Patent 2,978,904 and Grossman Patent 3,038,332. These prior forms of apparatus, however, are predominantly mechanical and are relatively expensive and complex. Further, these systems require extensive mechanical apparatus in addition to that normally provided to support a car body. Further, these systems often require complicated apparatus such as gyroscopes to compensate for the transverse rolling movement of the car body relative to the wheels. Alternatively, a measuring carriage is required which is supported on the road independently of the car bodyand the car body supporting Wheels.

Accordingly, it is an object of this invention to provide a dynamic railway track inspecting apparatus which is simple and economical in construction.

Another object of this invention is to provide a dynamic railway track testing system which can be quickly and easily installed and which utilizes the existing wheels and wheels suspension system of a railway car to determine the condition of the track.

A still further object of this invention is to provide a railway track testing apparatus which provides an indication of the relative condition of the railway track tested, which indication can be interpreted by a relatively unskilled worker.

Yet a further object of this invention is to provide simple railway track testing apparatus that automatically records a numerical indication of the relative condition of the railway track and automatically rejects indications caused by transverse car body roll.

' Briefly, acording to this invention a railway track testing apparatus is provided that comprises an electrical generating system which generates electrical signals indicative .of the difference in the vertical movements of the wheels of a pair of axially-aligned wheels with respect to a car body. From these generated signals, signals of a predetermined minimum frequency are selected or passed by a filter to one or more signal amplitude responsive circuits. Because transverse car body roll occurs at a relative low frequency, electrical signals generated by body roll will have a corresponding low frequency and ice will be attenuated or rejected by the filter because the filter has a low frequency cut-01f above the car body roll frequency. Each of a plurality of counters is coupled to the output of one of the amplitude responsive circuits and the resultant count of any one counter is an indication of the number of signals of that predetermined amplitude which have been generated. solely by the relative vertical movement of the wheels and independent of signals generated by car body roll.

Advantageously, a pair of transducers may be mounted on the car body. Each transducer is preferably mounted in cantilever fashion and carries a pair of strain gauges. These transducers are mechanically linked to opposite sides of a conventional truck, as through a pulley and flexible strand, to bend in response to vertical movements of one side of the truck relative to the other side of the truck. Also advantageously, the strain gauges act as variable resistors. These strain gauges are connected in a bridge circuit which includes a source of direct current. The output of the bridge is taken from the points intermediate t-he pairs of strain gauges and fed to an amplifier input circuit. This bridge output circuit algebraically combines currents caused by movements of the transducers relative to each other. The strain gauges on each transducer are serially connected across the source. Be cause of the simple nature of the transducers, and the manner of mechanically bending same, these transducers may be mounted on any existing car body. These and various other objects and features of the invention will be more clearly understood from the detailed description of the invention in conjunction with the drawings in which:

FIGURE 1 is a fragmentary side view in elevation showing a portion of a car body and a truck employed in this apparatus;

FIGURE 2 is a fragmentary end view in elevation of the structure of FIGURE 1 taken from the left-hand side of FIGURE 1 with portions removed;

FIGURES 3a and 3b are side elevational and plan views respectively, to an enlarged scale of the transducers employed in FIGURE 1 FIGURE 4 is a combined schematic and block diagram of the electrical portion of the railway track testing apparatus according to one illustrative embodiment of this invention;

FIGURE 5 is a schematic diagram of a portion of the electrical arrangement of FIGURE 4; and,

FIGURE 6 is a schematic representation of the remaining portion of the apparatus indicated in block form in FIGURE 4.

Referring now to the drawing, FIGURES 1 and 2 are a side view in elevation and an end view in elevation, respectively, of an installation of portions of the dynamic railway track testing apparatus according to one embodiment of this invention. In these figures, a car body 10 is mounted on a railway truck 11 by means of the usual mounting means 12 and the truck is supported on a pair of

axles

13, 14 in the usual manner. The truck includes the usual springs 15 which permit vertical movements of the truck frame 11 relative to the car body 10. Each axle has secured thereto the usual pair of rail-engaging wheels, such as wheels 16 and 17 on axle 13. These wheels engage a pair of rails 18, 19, respectively, which rails are to be tested or inspected by the apparatus according to this invention. Advantageously, the railway track testing apparatus includes a pair of

transducers

20, 21 each mounted on .a

suitable angle bracket

22, 23, respectively, in a cantilever fashion on the bottom 24 of the body 10 and projecting generally transversely relative to the car body 10.

Each transducer is connected to an end of the axle 13 by a mechanical arrangement which normally places the transducers under substantially equal tension. For transducer this arrangement includes a wire rope passing over a pulley 26 secured by .a suitable bracket 27 to the bottom 24 of the car body 10. The wire rope 25 is connected to journal box for the left end of the axle 13, as viewed in FIGURE 2. Similarly, the transducer 21 is coupled to journal box 37 on the right-hand end of axle 13, as viewed in FIGURE 2, by means of a wire rope 28 passing over a suitable pulley 29 in the same direction as the wire rope 25 passes over the pulley 26.

With this mechanical coupling between the

transducers

20, 21 and the opposite ends of the axle 13, vertical movement of the wheels 16, 17 in the same direction will produce movements or deflections of the

transducers

20, 21 in the same direction relative to the longitudinal dimension of car body 10. For example, if both ends of axle 13 move downwardly, both

transducers

20, 21 will be defiected to the right relative to the view of FIGURE 1. Similarly, vertically upward movements of both wheels 16 and 17 relative to body 10 will produce deflection of the

transducers

20, 21 to the left as viewed in FIGURE 1. The electrical portions of

transducers

20, 21 are connected to effectively cancel the effects of these simultaneous movements of the transducers in the same direction, in a manner which will be subsequently described. Thus the movements of the

transducers

20, 21 will be indicative of only the vertical movement of wheel 15 relative to wheel 16 resulting from relative undulations of the rails 18 and 19, respectively. Also the magnitude of these movements and the resulting amplitude of the transducergenerated signals will be proportional to the magnitude of these undulations.

Transducers

20, 21 are identical and accordingly only transducer 20 is shown in FIGURES 3a and 3b, respectively. Transducer 20 is in this particular example a relatively thin strip of fiberglass preferably of the order of of an inch in thickness having a width of 1 inch and a length of approximately 13 inches. The transducer 20 includes a base section 32 which is secured to the mounting bracket 22 by means of a suitable bolting arrangement in which bolts pass through the

holes

33, 34 in the base section 32 and the transducer 20 is mounted in cantilever fashion to bend in a horizontal plane relative to a vertical line 35.

Strain gauges

36 and 38 are mounted identical distances from the vertical line 35 on opposite sides of the fiberglass strip 31. These strain gauges may be any known type of strain gauge which acts as a variable resistance, the resistance of which varies as a function of the bending of the strain gauge relative to its longitudinal axis. One example of this type strain gauge is shown and described in detail in Geyling Patent 3,023,627.

The resistance of strain gauge 36, shown in full lines in FIGURES 3a and 3b, decrease as the eyelet 42 is pulled downwardly relative to the view of FIGURE 3b and the resistance of strain gauge 38 increases in value by this same movement. Conversely, movement of the eyelet upwardly relative to the view of FIGURE 312 causes the resistance of strain gauge 36 to increase and causes the resistance of strain gauge 38 to decrease. The coupling between the wire rope and the end of the transducer remote from base section 32 will now be described in detail.

The opposite end of the fiberglass strip 31 from the base section 32 is provided with an oval slot 40 which receives a suitable double eyelet 42 which may be longitudinally, slidably held relative to the strip 31 by any suitable means such as a pair of opposed collars 43. With this arrangement, the eyelet 42 slides in the slot 40 to prevent longitudinal loading of the strip 31. Stated in another manner, the eyelet 42 is free to move along slot 40 to compensate for the change in radius as strip 31 is deflected. The

transducers

20 and 21 are each placed under tension by a length of elastic shock cord 44 which is connected to the other side of the double eyelet 42 and to a suitable anchor 45 on the body 10.

A corresponding pair of

strain gauges

46 and 48 mounted on the transducer 21 are connected to the strain gauges 36 and 38 to define a bridge circuit, as shown in the left-hand portion of FIGURE 4. A battery 47 is connected between two of the diagonals of the bridge circuit and the other diagonals of the bridge circuit are connected as input leads to a preamplifier 50. Thus the variations in the resistances of the strain gauges in the bridge circuit cause currents in the respective legs of the bridge which are algebraically combined at the bridge diagonals. Changes in one leg which are not accompanied by corresponding variations in the opposite leg of the bridge circuit will result in the generation of current which will flow into the input of the preamplifier 50. This bridge arrangement of the strain gauges and the direct current source 47, therefore, constitute a means for algebraically combining electrical signals indicative of the relative vertical movement of the wheels 15, 16.

The output of the bridge circuit fed to the preamplifier 50 is a complex wave form containing information indicative of car body roll and relative vertical wheel movement. At speeds above 35 miles per hour, the car body roll component is in a frequency range usually below one cycle per second and the relative vertical wheel movement component is in the frequency range above two cycles per second. The roll frequency is constant at all speeds for a given car and is determined by the mass of the car and the spring constant. The frequency of cross level variations varies with speed and is above 2 c.p.s. at speeds greater than 35 miles per hour. This complex signal is amplified by the preamplifier 50 and is fed to a high pass type filter 52 which has a cut-off frequency of 1 /2 cycles per second. Thus high pass type filter 52 will attenuate signals of a frequency below 1 /2 cycles per second, which includes those signals indicating car body roll. High pass filter 52 will, however, transmit the signals indicative of cross level variations to a DC amplifier 54.

The output of DC amplifier 54 is fed to the input .of three separate

amplitude detector circuits

56, 57 and 58, each having its input adjusted to respond to a different signal amplitude. The outputs of

amplitude detectors

56, 57 and 58 are individually connected to individual pulse counters 60, 61 and 62, respectively. These pulse counters will each indicate a count, preferably in digital form, of the number of pulses which have been detected by the

respective amplitude detectors

56, 57 and 58. Thus the count of the pulse counter 60, 61 and 62 will in fact be a relative indication of the road level, which digital indication will be simple to understand and will not require the interpretation by a skilled technician as would be the case if it were a complex wave form or a multi-frequency wave form. Further, the pulse counter will deliver an indication of the roadway condition independent of car body roll and car body vertical movements because the effects of the car body roll have been eliminated by the high pass filter 52 and the effects of car body vertical movement are cancelled by the strain gauge bridge connection.

As stated above, the car body roll frequency does not vary with speed. Therefore, only filter 52 with a cut-off frequency of 1 /2 cycles per second is needed. The system will work at any speed greater than 35 miles per hour without any modifications to filter 52.

FIGURE 5 and 6, when placed end to end with FIGURE 5 to the left and FIGURE 6 to the right, constitute a schematic representation of portions of one embodiment of this invention shown in block diagram in FIGURE 4. The terminals 49, 51 correspond to the input terminals to the preamplifier 50 and the output terminals from the gauge bridge circuit shown in FIGURE 4, with terminal 51 being the common ground for the system. The preamplifier includes a pair of

transistors

70, 71 connected in a direct current amplifying arrangement with a source of potential of approximately 12 volts applied between terminal 72 and common ground terminal 51. The base of transistor is biased by a pair of resistors 75, 76 connected in series between

terminals

72 and 51 and with the intermediate point connected to the base of transistor 70. A de-coupling resistor 77 is connected between terminals 49 and the base of transistor 70. The collector of transistor 70 is connected to positive battery terminal 72 to a suitable resistor 78. The resistor 78 includes part of a base biasing network for transistor 71 which includes serially-connected

resistors

79 and 80 with the base of transistor 71 connected intermediate these resistors. The emitter of transistor 70 is connected to the common ground 51 through a resistor 81. The collector of transistor 71 is connected to the positive battery terminal 72 by means of a resistor 84. The emitter of transistor 71 is connected to the ground 51 through a suitable resistor 86. The output of this two-stage direct current amplifier is fed to the input terminals 85, 51 of the high pass filter 52.

A shunt capacitor 88 is connected across the input terminals 85, S1 of a high pass filter 52. High pass filter 52 includes a series of three serially-connected

capacitors

92, 93 and 94 serially connected between the filter input terminal 85 and a filter output terminal 95. A pair of shunt arms are connected from the points intermediate these series of capacitors to ground 51 and include a first inductance 96 and a serially-connected resistor 97 and a second inductance 98 and its serially-connected resistor 99. A capacitor 100 is connected in shunt across the

output terminals

95, 51 of high pass filter 52, which terminals are also the input terminals of amplifier 54.

Capacitors

88, 100 provide a high frequency cut-01f for the filter. The capacitors effectively flatten out the response of the filter for a high frequency roll-01f type response.

Amplifier 54 is a differential amplifier producing an output that can be positive or negative with respect to ground. This amplifier includes a pair of

transistors

101, 102 connected in a well-known differential amplifier arrangement. This differential amplifier arrangement is described in detail on p. 111 of the 1964 edition of General Electric Transistor Manual. The principal distinction of the instant differential amplifier from that shown in the text is the grounding of the base of transistor 102 through a resistor 109. In the instant differential amplifier, the input terminal 95 is connected to the base of transistor 101 through a resistor 103 and the collector of transistor 101 is connected to a suitable positive battery terminal 72 through a resistor 104. The emitter of transistor 101 is connected to a source of negative potential indicate-d by terminal 110 through a pair of resistors 105, 106. Transistor 102 has its emitter connected through a resistor 107 and resistor 106 to the negative terminal 110. As previously mentioned, the base of transistor 102 is connected to ground through a resistor 109 and the collector is connected through a resistor 108 to the source of positive potential.

The output of this differential amplifier is taken from the collector of transistor 101 and is fed through the bridge rectifier 55.

Rectifier bridge 55 includes a pair of

rectifiers

112, 113 connected to the collector electrode of the transistor 101 and a second pair of

rectifiers

114, 115 all connected in a well-known bridge structure to deliver a direct current output from terminals 116, 117 in a manner wellknown in the art. Terminal 116 is the effective ground for the amplitude detector circuit while terminal 117 is the other output terminal connected to the other detector circuits. Because of the identity of the

amplitude detector circuits

56, 57 and 58, only amplitude detector 56 will be described in detail.

The amplitude detector 56 includes three

transistors

118, 119 and 120 connected in cascade. Negative potential is supplied to these transistors from a source indicated by a terminal 121. Transistor 118 has its base connected to a variable resistor 122, which variable resistor is connected in series with a resistor 123, the series combination being connected between the negative terminal 121 and the effective ground terminal 116. The variable tap of resistor 122 is connected to the signal input terminal or signal output terminal 117 of the bridge rectifier 55. The

collector electrode of transistor 118 is connected to the source of negative potential 121 through a suitable resistor 124. The resistor 124 is part of a voltage divider including serially-connected

resistors

125 and 126. Resistor 126 is connected to the capacitive ground terminal 116 previously described. The emitters of

transistors

118, 119 are connected to the effective ground through a resistor 127. The base of transistor 118 is connected to the voltage divider 124, 125, 12-6 at a point

intermediate resistors

125 and 126. The collector of transistor 119 is connected to the negative terminal 121 through a suitable resistor 128. The output of the transistor 119 is fed through a serially-connected resistor 130 connected between the collector of transistor 119 to the base of transistor 120. The emitter of transistor 120 is directly connected to the negative terminal 121 and the collector of transistor 121 is connected to ground terminal 116 through a suitable resistor 132. The output of transistor 120 is taken from the collector and is fed through a serially-connected resistor 133 to the base of transistor 134. The emitter of transistor 134 is connected to ground terminal 116 and the collector through a suitable solenoid 135 to a source of negative potential indicated by a terminal 136. Solenoid 135 is a part of pulse counter 60 and actuates a suitable counting mechanism of any convenient form.

Adjusting the position of the variable tap on the resistor 122, varies the amplitude level at which the amplitude detector transistor 118 will trigger in response to signals delivered from terminals 116, 117 of rectifier bridge 55. In setting the resistors corresponding to resistor 122 in each of

amplitude detectors

57, 58, the settings are preferably step-wise settings such that each successive amplitude detector requires a higher level of input signal to trigger the respective amplitude detector. For example, transistor 118 may be biased by adjusting the tap on the resistor 122 such that the transistor 118 triggers in response to an input signal of 2 volts. Similarly, the resistor corresponding to resistor 122 in amplitude detector 57 may be set so that the transistor corresponding to transistor 118 in amplitude detector 57 responds to a signal voltage of 4 volts. The variable resistor in amplitude detector 58 may be set so that the transistor corresponding to transistor 118 responds only if the signal voltage level exceeds 6 volts. These figures, however, of signal voltage levels are merely for the purpose of indicating relative levels and should not be considered as limiting upon any particular step or of any ultimate magnitude of signal to which the detectors respond. It is possible to make satisfactory measurements with only two amplitude detectors and their associated counters.

Because the transistor 118 of amplitude detector 56 is biased to respond to voltage signals above 2 volts in amplitude, the count indicated by counter 60 which includes solenoid 135 will be a total count of all pulses leaving the direct current amplifier 54 which are in excess of 2 volts. Similarly, the counter 61 connected to the output of amplitude detector 57 will record a count indicative of the number of pulses of at least 4 volts in amplitude delivered from the direct current amplifier 54. Also, pulse counter 62 will record those pulses leaving direct current amplifier 54 which equal or exceed 6 volts. Thus the count of the counters 60, 61 and 62 will be an indication in digital form of number and relative amplitude of roadbed undulations and thus the relative condition of the roadway under test which in this particular instance comprises the rails 18, 19 in FIGURE 2.

The advantages of this railway truck inspecting apparatus are numerous. Because the electrical system is provided with a frequency responsive network which rejects or attenuates low frequency signals generated by the strain gauges in response to car body roll, the requirement for the gyroscopes previously employed to eliminate the effects of car body swaying or the requirement of a separate measuring carriage for this same purpose are obviated. Further, because the strain gauges mounted on the respective transducers are connected in a bridge circuit to algebraically combine the resultant generated signals, requirements for differential mechanical connection to the respective wheels is eliminated. Still further, because the electrical system is employed to actuate a series of counters through different amplitude responsive circuits, the count of each counter is indicative of the number of signals of that predetermined amplitude which have been generated by the transducers. This numerical value constitutes a relative indication of road conditions which can be quickly recorded and understood by one having no previous skill in roadway inspection.

The present invention will thus be seen to effectively accomplish the objects enumerated herein above. It will be realized that various changes and substitutions may be made to the specific embodiments disclosed herein for the purpose of illustrating the principles of this invention, without departing from these principles. Therefore, this invention includes all modifications encompassed within the spirit and scope of the following claims.

What is claimed is: 1. In a dynamic railway track inspecting apparatus adapted to be used on a railway car having a car body, an axle with a pair of wheels thereon and truck means mounting said wheels beneath said body, the combination comprising electrical means for producing electrical signals indicative of the difference in vertical movement of said wheels with respect to the car body; frequency responsive means for responding only to said electrical signals above a predetermined frequency; and, indicating means responsive to said signals above said predetermined frequency.

2. Apparatus according to claim 1 including amplitude responsive means coupled to the output of said frequency responsive means for responding to those of said signals which have predetermined differences in amplitude and delivering output pulses in response thereto.

3. The combination according to claim 2 wherein said amplitude responsive means includes a plurality of amplitude responsive detectors each having an input coupled to said frequency responsive means and wherein said counting means includes a plurality of digital counters each coupled to the output of one of said amplitude responsive detectors to give a digital count of the output pulses from each respective detector.

4. Roadway level detecting apparatus comprising: electrical means for generating a composite wave form indicative of amplitude and frequency of the difference in vertical movement of a pair of axially aligned wheels relative to a car body supported on the wheels; 1

frequency responsive means coupled to the output of said electrical means for delivering an output signal representative of the components of said wave form above a predetermined frequency,

amplitude responsive means for delivering output signals indicative of the number of times the amplitude of said frequency responsive means output signal eX- ceeds predetermined values.

5. The apparatus of claim 4 wherein said electrical means includes a pair of transducer means each coupled to one of said wheels, each transducer means including a pair of strain gauges, said gauges being connected together to algebraically combine the outputs of said pairs of gauges.

6. The apparatus of claim 4 wherein said electrical means includes two pairs of strain gauges coupled in a bridge circuit and a direct current source coupled to two terminals of said bridge circuit and wherein said frequency responsive means includes a high pass filter having its input coupled to said bridge circuit and its output coupled to said amplitude responsive means. v

7. The combination according to claim 4 wherein said amplitude responsive means includes a plurality of trigger circuits, each responsive to a different input signal amplitude and each having its input connected to the output of said frequency responsive means.

8. The combination according to claim 7 further comprising a plurality of counting means each coupled to one of said trigger circuits for counting the output pulses thereof.

9. In a dynamic railway track inspecting apparatus adapted to be used on a railway car having a car body, an axle with a pair of wheels thereon, and truck means mounting said wheels beneath said body, the combination comprising electrical means for producing electrical signals indicative of the difference in vertical movement of said wheels with respect to the car body; frequency responsive means for responding only to said electrical signal above a predetermined frequency; differential amplifier means coupled to the output of said filter for producing output signals of positive and negative polarity with respect to ground; rectifier means coupled to the output of said differential amplifier for producing an output of a single polarity in response to input signals of positive and negative polarity; amplitude detector means coupled to the output of said rectifier means for responding to signals of predetermined amplitude; and, counter means coupled to said amplitude detector means for indicating the number of pulses of predetermined amplitude delivered from selected ones of said amplitude detector means.

10. In a dynamic railway track inspecting apparatus according to claim 9, said electrical means for producing electrical signals indicative to the vertical movements of said wheels relative to each other comprising a pair of transducers means each coupled to one of said means, each transducer means including a pair of strain gauges, said strain gauges being connected together in a bridge circuit to algebraically bind the outputs of said pairs of said gauges.

11. The combination according to claim 9 wherein said frequency responsive means transmits to said differential amplifier means only signals above 2 cycles per second.

12. The combination according to claim 9 wherein said rectifier means includes a rectifier bridge coupled to said differential amplifier and to said amplitude detector means.

13. The combination according to claim 9 wherein said amplitude detector means comprises a plurality of detector stages each responsive to signals of different predetermined voltage levels.

References Cited UNITED STATES PATENTS 2,118,105 5/1938 Perry 33 141.5

S. CLEMENT SWISHER, Acting Primary Examiner.

DONALD O. WOODIEL, Examiner.